#include <glad/glad.h>
#include <GLFW/glfw3.h>

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>

// https://learnopengl.com/code_viewer_gh.php?code=includes/learnopengl/shader_m.h
#include <shader_s.h>
// https://learnopengl.com/code_viewer_gh.php?code=includes/learnopengl/camera.h
#include <camera.h>
#include <iostream>
void InitGLFW();
bool CreateWindow();
bool InitGLAD();

// 窗口大小改变时调用
void framebuffer_size_callback(GLFWwindow *window, int width, int height);
void mouse_callback(GLFWwindow *window, double xposIn, double yposIn);
void scroll_callback(GLFWwindow *window, double xoffset, double yoffset);
void processInput(GLFWwindow *window);
unsigned int loadTexture(const char *path);

// settings 窗口宽高
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

// 相机
Camera camera(glm::vec3(0.0f, 0.0f, 6.0f));
float lastX = static_cast<float>(SCR_WIDTH) / 2.0;
float lastY = static_cast<float>(SCR_HEIGHT) / 2.0;
bool firstMouse = true;

// timing
float deltaTime = 0.0f; // time between current frame and last frame
float lastFrame = 0.0f;

// lighting
glm::vec3 lightPos(0.5f, 0.5f, 1.0f);

GLFWwindow *window;

int main()
{
    InitGLFW(); // 初始化GLFW

    bool isCreated = CreateWindow(); // 创建一个窗口对象
    if (!isCreated)
        return -1;
    bool isGLAD = InitGLAD(); // 初始化GLAD，传入加载系统相关opengl函数指针的函数
    if (!isGLAD)
        return -1;

    // 启用深度测试
    glEnable(GL_DEPTH_TEST);

    // 构建和编译着色程序
    Shader lightingShader("shader/P1_Basic/08_LightModel/lighting_maps.vs", "shader/P1_Basic/08_LightModel/lighting_maps.fs");
    Shader lightCubeShader("shader/P1_Basic/08_LightModel/light_mrt_cube.vs", "shader/P1_Basic/08_LightModel/light_mrt_cube.fs");

    // 设置顶点数据(和缓冲区)并配置顶点属性
    // 1.设置立方体顶点输入  一共需要36个顶点
    float vertices[] = {
        // positions          // normals           // texture coords
        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,
        0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f,
        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
        0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
        -0.5f, 0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,

        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
        0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
        0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
        -0.5f, 0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, 0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,

        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
        -0.5f, 0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, -0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
        -0.5f, -0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
        -0.5f, 0.5f, 0.5f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
        0.5f, 0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
        0.5f, -0.5f, -0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
        0.5f, -0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,

        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,
        0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f,
        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,
        0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,
        -0.5f, -0.5f, 0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f,
        -0.5f, -0.5f, -0.5f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f,

        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
        0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f,
        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
        0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
        -0.5f, 0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
        -0.5f, 0.5f, -0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f};
    // 2.设置索引缓冲对象
    unsigned int VBO, cubeVAO;
    glGenVertexArrays(1, &cubeVAO);
    glGenBuffers(1, &VBO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    glBindVertexArray(cubeVAO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)(6 * sizeof(float)));
    glEnableVertexAttribArray(2);

    // second, configure the light's VAO (VBO stays the same; the vertices are the same for the light object which is also a 3D cube)
    unsigned int lightCubeVAO;
    glGenVertexArrays(1, &lightCubeVAO);
    glBindVertexArray(lightCubeVAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    // note that we update the lamp's position attribute's stride to reflect the updated buffer data
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0);

    // 加载纹理
    unsigned int diffuseMap = loadTexture("image/04_Textures/container2.png");

    // shader configuration
    // --------------------
    lightingShader.use();
    lightingShader.setInt("material.diffuse", 0);

    // 循环渲染
    while (!glfwWindowShouldClose(window))
    {
        // 计算帧间隔时间
        float currentFrame = static_cast<float>(glfwGetTime());
        deltaTime = currentFrame - lastFrame;
        lastFrame = currentFrame;

        // 输入
        processInput(window);

        // 渲染
        // 清除颜色缓冲
        glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
        // 清除深度缓冲
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // be sure to activate shader when setting uniforms/drawing objects
        lightingShader.use();
        lightingShader.setVec3("light.position", lightPos);
        lightingShader.setVec3("viewPos", camera.Position);

        // light properties
        lightingShader.setVec3("light.ambient", 0.2f, 0.2f, 0.2f);
        lightingShader.setVec3("light.diffuse", 0.5f, 0.5f, 0.5f);
        lightingShader.setVec3("light.specular", 1.0f, 1.0f, 1.0f);

        // material properties
        lightingShader.setFloat("material.shininess", 64.0f);

        // view/projection transformations
        glm::mat4 projection = glm::perspective(glm::radians(camera.Zoom), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
        glm::mat4 view = camera.GetViewMatrix();
        lightingShader.setMat4("projection", projection);
        lightingShader.setMat4("view", view);

        // world transformation
        glm::mat4 model = glm::mat4(1.0f);
        lightingShader.setMat4("model", model);

        // bind diffuse map
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, diffuseMap);

        // render the cube
        glBindVertexArray(cubeVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        // also draw the lamp object
        lightCubeShader.use();
        lightCubeShader.setMat4("projection", projection);
        lightCubeShader.setMat4("view", view);
        model = glm::mat4(1.0f);
        model = glm::translate(model, lightPos);
        model = glm::scale(model, glm::vec3(0.2f)); // a smaller cube
        lightCubeShader.setMat4("model", model);

        glBindVertexArray(lightCubeVAO);
        glDrawArrays(GL_TRIANGLES, 0, 36);

        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // 可选:一旦资源超出其用途，就取消分配所有资源:
    glDeleteVertexArrays(1, &cubeVAO);
    glDeleteVertexArrays(1, &lightCubeVAO);
    glDeleteBuffers(1, &VBO);
    // 释放/删除之前的分配的所有资源
    glfwTerminate();
    return 0;
}

void InitGLFW()
{
    // 初始化GLFW
    glfwInit();
    // 配置GLFW  第一个参数代表选项的名称，我们可以从很多以GLFW_开头的枚举值中选择；
    // 第二个参数接受一个整型，用来设置这个选项的值。
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
}
bool CreateWindow()
{
    // 创建一个窗口对象
    window = glfwCreateWindow(800, 600, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        // 创建失败，终止程序
        glfwTerminate();
        return false;
    }
    // 将我们窗口的上下文设置为当前线程的主上下文
    glfwMakeContextCurrent(window);
    // 设置窗口大小改变时的回调函数
    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
    // 设置鼠标移动回调函数
    glfwSetCursorPosCallback(window, mouse_callback);
    // 设置滚轮滚动回调函数
    glfwSetScrollCallback(window, scroll_callback);

    // 隐藏并捕捉鼠标
    // glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

    return true;
}
bool InitGLAD()
{
    // 初始化GLAD，传入加载系统相关opengl函数指针的函数
    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
    {
        std::cout << "Failed to initialize GLAD" << std::endl;
        // 初始化失败，终止程序
        return false;
    }
    return true;
}

// 窗口大小改变时调用
void framebuffer_size_callback(GLFWwindow *window, int width, int height)
{
    // 设置窗口的维度
    glViewport(0, 0, width, height);
}

// 输入
void processInput(GLFWwindow *window)
{
    // 当用户按下esc键，我们设置window窗口的windowShouldClose属性为true
    // 关闭应用程序
    if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
        glfwSetWindowShouldClose(window, true);

    if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS)
        camera.ProcessKeyboard(FORWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS)
        camera.ProcessKeyboard(BACKWARD, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS)
        camera.ProcessKeyboard(LEFT, deltaTime);
    if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS)
        camera.ProcessKeyboard(RIGHT, deltaTime);
}

// 鼠标移动回调函数
void mouse_callback(GLFWwindow *window, double xposIn, double yposIn)
{
    // 长按T键，鼠标才能控制相机
    if (glfwGetKey(window, GLFW_KEY_1) != GLFW_PRESS)
        return;

    float xpos = static_cast<float>(xposIn);
    float ypos = static_cast<float>(yposIn);

    if (firstMouse)
    {
        lastX = xpos;
        lastY = ypos;
        firstMouse = false;
    }

    float xoffset = xpos - lastX;
    float yoffset = lastY - ypos; // reversed since y-coordinates go from bottom to top

    lastX = xpos;
    lastY = ypos;

    camera.ProcessMouseMovement(xoffset, yoffset);
}

// 鼠标滚轮滚动回调函数
void scroll_callback(GLFWwindow *window, double xoffset, double yoffset)
{
    camera.ProcessMouseScroll(static_cast<float>(yoffset));
}
unsigned int loadTexture(char const *path)
{
    unsigned int textureID;
    glGenTextures(1, &textureID);

    int width, height, nrComponents;
    unsigned char *data = stbi_load(path, &width, &height, &nrComponents, 0);
    if (data)
    {
        GLenum format;
        if (nrComponents == 1)
            format = GL_RED;
        else if (nrComponents == 3)
            format = GL_RGB;
        else if (nrComponents == 4)
            format = GL_RGBA;

        glBindTexture(GL_TEXTURE_2D, textureID);
        glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
        glGenerateMipmap(GL_TEXTURE_2D);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

        stbi_image_free(data);
    }
    else
    {
        std::cout << "Texture failed to load at path: " << path << std::endl;
        stbi_image_free(data);
    }

    return textureID;
}